I've been admiring some of the flickr photos withsharp color, and often they speak of photomanipulation software to produce high dynamic range. Does anyone know whether this is something GIMP will do?Thanks,Helen

I don't know of any HDR plugins (If anyone does know of one, please point me at any any that work for the current 2.2x version of the gimp) for the gimp, but it's pretty easy to make a "DRI" picture. If you camera is capable of making bracket shots or you have a tripod stable enough for you to set this up yourself. take more then one shot with different exposure settings. Break up the pictures with selections or masks to pick out the parts you want to combine and put this back together into one picture. Here's my first attempt at this, made with two pictures.

There's one other was to make DRI pictures, if your camera can shoot in RAW mode, and you use a RAW reader that is capable of making pre-conversion adjustments to the picture (I use UFRAW myself). Do the exposure adjustments while still in raw, and import into the GIMP. do this twice with differnt settings. Using the method I talked about at the top of this post, put them back together into one picture.

HDR produces images with a large range of luminance (typically of the order of 10¹², or a trillion). The problem is that, unless you have an HDR graphic card and state of the art monitor, your monitor can only display a range of the order of 300. So what do programs like Photomatix and Photoshop do? They compress that large variation into the 256 possibilities displayable on your average monitor by a process called tone mapping. There are various ways, or algorithms, to do this but typically they preserve local detail (and contrast) at the expense of large-scale contrast. So you end up with your typical detailed, colourful and tonally flat "HDR".

Exposure blending is a different animal altogether. It doesn't construct an interemediate file with a high dynamic range - it just picks what the user selects from 2 (or more) images with your normal 300 range. The end result is different, too - large scale contrast is usually not so compromised but, on the other hand, small scale contrast isn't really enhanced either. In general exposure blending requires more work too as there's more liberty for the user to make decisions about where and how to blend.

Gimp can't do true HDR because the Gimp engine is limited to 8 bits per colour channel.

Dedicated HDR software such as the Photoshop HDR subsystem and Photomatix use either 16, 24 or 32 integer bits per colour channel or floating point representation to provide extended dynamic range. Gimp cannot do that, and there is no indication from the Gimp development team that anything will change in the foreseeable future.

There is, however, a fork of the Gimp 1.x tree called cinepaint, which has been developed for high colour depth applications (mainly CGI) and is used by a lot of the big movie production houses. It has an experimental HDR plugin, which in its current state of development, can generate HDR images from 8 bit per channel sources. No word on when either direct 12 bit Bayer or converted 16 bit RGB material import will be implemented

It's not gimp but you might be interested in creating, handling and tonemapping HDR images with pfstools. Here's a short overview. I use gimp for some parts of the workflow, like NEF handling, cropping, retouche..

I haven't done any true HDR yet, but I think I've found a method that closely approximates the final product many people get. I jotted down what to do on the page for this photo:

I need to try it out on some more interesting subjects, though. I tried my process on the sample photos listed at the mkhdr website, and it seemed to produce a fairly good result. I'm not exactly sure how the licensing works for those photos, so I haven't posted what it looks like.

proud education [deleted]
12 years ago

A simple way to do exposure blending if you shoot in raw is to use the Raw software to tweak the exposure to bring out the areas of the picture you want. You then process these to TIF and open the GIMP.

Use one as a base layer (I usually use the most shadowy layer as the base) and then layer up the other images on top. As they are all the same size select all and paste gives optimal alignment.

Then use a layer mask on the upper layers and paint in the elements you want to show through.

Another little trick I found in GIMP itself to, say improve a washed out sky is to duplicate the layer with the best sky exposure and then set the blend mode to overlay. If this overly darkens other areas youcan use layer masks again to remove the blend from that area

physical guitar [deleted]
12 years ago

Is it just me or do the HDR pics looks completely awful? They look so fake. They remind me of the technicolor movies ...

I've read some tutorials. as I don't like to create masks and so on, i tried another approach.

I've just stacked all the images in layers in gimp. (brightest the lowest and darkest the most upper one). Than I added a layer mask to every layer (except for the brightest one)After this I just divided 100% by the number of pictures and took a gray with this brightness (in this case almost black). With this color I filled all the layer masks. This makes the images allmost transparent and (only 7% left) and let's the layers beyond "shine thru".That's it. One can discuss on the results, but i'm almost atisfied for a "first".Just wished I had some more RAM, with only 512MB is definitely not funny anymore with 14 layers each 2048x1536.

For this photo the Uniform/High/Low setting didn't have much effect, although I would assume that it refers to modifying the whole image/just the light parts/just the dark parts.

The Scale setting produces something very like an edge strength imageif set too low, so medium to high values seem better.

The Scale Division setting seemed to have no great impact on the result,other than smaller values possibly producing a slightly smoother (andfaster) result. A value of zero produced a completely black image.

The Dynamic setting gives more natural looking colours at highervalues, and much more saturated ones at lower values.

It looks like you can get a slightly more pleasing effect by decomposingthe image to HSV, and only filtering the Value layer (converted toRGB first) then re-composing (converting back to greyscale first):

Below is an attempt to use exposure blending in Gimp using an underexposed night image in combination with a day image and an overexposed day image. The lights of the photo exhibition show up nicely and give it a nice strange effect.

The night photo really only shows up in the lights over the photos. Also you see the lights shine on the ground.I am going to make more attempts at this. The idea was stolen from Magritte's day/night paintings by the way.

I think an awful lot of HDR images (actually, they're not HDR images, they're blends of differently exposed images, HDR is quite different) look really bad. This technique has been around as long as digital imaging, and what it can be used for are images where there's almost a definite line along which you can blend from one image to another (in fact that's how it always used to be done). Running these automated scripts on any old bracketed set makes can make a real mess. Having said that they can look great. Mulad's image above is a great example, it doesn't look like he's done anything to it, it looks like he just has a magic camera which takes great tones and has a huge dynamic response. Some of the others look great too.

There seems to be quite a bit of purist stuff out here ("HDR is NOT the same as exposure blending" etc etc) but it seems to me there is a place for this stuff, whatever you want to call it, solely in terms of artistic merit.

For me, there are two possible reasons for using HDR (or exposure blending, okay, okay):

There are others in the same place - www.dpchallenge.com/photo_gallery.php?GALLERY_ID=53 - some more successful than others, but all of them go beyond normal photography and into (at least attempted) art. Yes, some people will get sniffy about this, and others will be sniping cos they "didn't use RAW images" or some such, but it seems to me one can only judge photography on its artistic merits. The camera, after all, lies all the time, especially now with the help of Photoshop/Gimp. Good thing too.

I tried HDR a few times with no success but that is because I have no idea how to use layers or anything with GIMP and got frusturated... after hours of trying to follow a PS tutorial and using GIMP. Not the best idea unless you have used ONE of them before. With that said, check out the flickr ID: _UNCOMMON

This guy produces absolutely stunning images using HDR techniques... to me anyway. Some of the most interesting images I have ever seen. He also uses Lucisart and some other stuff but he is pretty new at all of it apparently... I think he started a cpl yrs ago. Some of the lucisart stuff looks more like...caricature is the only word I can think of but he is super talented and doesn't go over the top on the HDR. If you like his stuff, go through the stream thoroughly and click on a lot of images...LOTS of them. You will find here images where he actually shows the before and after and how he did it..makes it seem super easy. Notice his composition as well... For my novice eyes, this guy found his true calling whether or not he sells his stuff and makes money is irrelevant (although i think he could make a LOT of money in the art world if he chose to). I think he just finds (or I hope he does anyway) that he is able to express how he sees the world through his camera and processing. BTW- He does nto have alot of expensive gear.... 8mp canon rebel and a cpl lenses, the nicest being a sigma 10-20 I think. Well worth the time if you like HDR!

I don't know if this topic is still being discussed, but I found a script for Gimp that appears to be working well in version 2.6:registry.gimp.org/node/24500

I'll try it out on actual real-life footage later today and post the results. For now the approach is astoundingly simple. You take three shots at different exposure-levels, stack them on top of each other, run the script and watch as magic happens. :-)